We have investigated the phase behaviour as a function of enantiomeric excess of a fluorosubstituted tolan derivative, FH/FH/HH18BTMHC, using high-resolution adiabatic scanning calorimetry (ASC). This substance exhibits a direct TGB to BP transition. Mixing (R) and (S) enantiomers permits us to vary the chirality of these mixtures without much effect on other parameters. Changes in transition temperature are studied, as well as the enthalpy changes and latent heats at the various transitions which can be measured directly using ASC. A supercritical BPIII-I transition evolving towards a critical point is observed.